Typically, a deodorising composition will attempt to significantly reduce or prevent body odour by reducing either perspiration or the number of viable micro-organisms on the body surface as represented herein by skin. The former is usually referred to as an antiperspirant composition and the latter a deodorant. Other compositions attempt to mask body malodours using perfumes.
Compositions reducing perspiration often comprise a metal salt, such as an aluminium or zirconium salt, which blocks the sweat pores. This method is very simple and has proven to be beneficial, yet perspiration is rarely reduced by more than 50%.
Deodorants, on the other hand, reduce the numbers of viable micro-organisms on the surface of the skin. It is well known that sweat is usually odourless until it has been degraded by the skin microflora. Typical deodorants include ethanol and triclosan (2′,4,4′-trichloro,2-hydroxy-diphenyl ether) which is a well known anti-microbial agent. However, the deodorising effect obtained with such deodorants wears off with the passage of time and the microflora progressively recover their numbers.
There is, therefore, a continuing requirement for effective and long lasting antiperspirant deodorant compositions for the market. The problem to be solved is not simply reducing sweating and initial microbial numbers on the body surface; equally important is maintaining low microbial numbers (particularly low bacterial numbers) on the body surface (particularly in the most malodorous areas, eg. the axilla).
Transition metal chelators have previously been incorporated into antiperspirant deodorant compositions as formulation aids. U.S. Pat. No. 5,516,511 (Procter and Gamble Co.) discloses particular antiperspirant gel compositions in which chelators are used during manufacture to prevent reaction between the active and the primary gellant, the latter component comprising 12-hydroxystearic acid or a derivative thereof. U.S. Pat. No. 5,849,276 (Procter and Gamble Co.) mentions chelators in antiperspirant stick compositions, although such materials are stated to be optional “non-active” components. The gellants exemplified in this patent are again 12-hydroxystearic acid and derivatives thereof, and also N-lauroyl-glutamic acid dibutyl amide and 2-dodecyl-N.N′-dibutyl-succinamide.
Transition metal chelators have also been disclosed in simple deodorant compositions, that is to say, deodorant compositions excluding antiperspirant actives. U.S. Pat. No. 4,356,190 (Personal Products Co.) discloses the use of selected aminopolycarboxylic acid compounds for inhibiting malodour formation; WO 97/01360 (Concat Ltd.) claims a method of inhibiting bacterial growth using particular substituted polyaza compounds that show affinity for first transition series elements; WO 97/44006 (Ciba Speciality Chemicals Holding, Inc.) claims the use of nitrogen-containing complexing agents for the anti-microbial treatment of the skin and of textile fibre materials; and WO 97/02010 discloses the use of chelators selected from the succinic acid, glutaric acid, and phosphonic acid classes as bactericidal compounds.
Other patents indicate that transition metal chelators can improve the efficacy of specific known anti-microbials. WO 98/12399 (Public Health Research Institute of the City of New York) discloses improved performance of lanthionine-containing bacteriocins in compositions also comprising a transition metal chelator. WO 97/09974 (Laboratoire Medix) discloses compositions comprising chlorhexidine and a chelator. EP 0019670 B1 (Glyco Chemicals, Inc.) discloses anti-microbial compositions comprising a condensation product of 5,5-dimethyl hydantoin and formaldehyde in combination with a water-soluble chelating agent selected from ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) or the alkali metal salts thereof. U.S. Pat. No. 4,199,602 (Economics Laboratory, Inc.) discloses the potentiation of anti-microbial nitroalkanes by aminocarboxylic-type chelating agents. U.S. Pat. No. 5,688,516 (University of Texas System et al) discloses compositions comprising non-glycopeptide anti-microbials (other than vancomycin) in combination with a selection of components, including a chelating agent. WO 99/10017 (University of Texas System et al) discloses a method for controlling the growth of micro-organisms using a chelating agent and an anti-microbial agent. GB 1,420,946 (Beecham Group Ltd.) discloses that the activity of selected phenolic anti-microbials can be vastly increased by certain chelating agents, in particular the disodium salt of EDTA.